Estimation of hysteresis loss in Sm₁Ba₂Cu₃O_7−δ coated conductor via scanning Hall probe measurements with simultaneously applied field and current

다국어 초록 (Multilingual Abstract)

<P>The hysteresis loss in a Sm<SUB>1</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7−δ</SUB> coated conductor was estimated from magnetic field profiles measured by the scanning Hall probe method. Current, <I>I</I><SUB>a</SUB>, and magnetic field, <I>B</I><SUB>a</SUB>, were applied simultaneously; <I>B</I><SUB>a</SUB> was applied in the normal direction with respect to the tape surface. <I>B</I><SUB>a</SUB> and <I>I</I><SUB>a</SUB> were varied from <I>B</I><SUB>peak</SUB> to −<I>B</I><SUB>peak</SUB> and from <I>I</I><SUB>peak</SUB> to −<I>I</I><SUB>peak</SUB>, respectively, with the ratio α = <I>I</I><SUB>a</SUB>/<I>B</I><SUB>a</SUB> fixed during the variation. Three values of α were taken for the three load lines. The values of <I>B</I><SUB>peak</SUB>/<I>I</I><SUB>peak</SUB> were varied from 0 mT/0 A to 10.7 mT/116 A, 99.1 mT/50 A, and 298.2 mT/46.1 A, respectively, for the three load lines. From the measured values of magnetic field profiles, the current profiles were calculated by the iterative inversion method. From the current profiles, the flux density profiles and the hysteresis loss, <I>Q</I>, were then calculated for various values of <I>I</I><SUB>peak</SUB>(= α<I>B</I><SUB>peak</SUB>) in each load line. The results were compared with theoretical calculations based on Brandt’s model. When <I>B</I><SUB>peak</SUB> was about 300 mT, the estimated values of <I>Q</I> were several times smaller than the theoretical values of <I>Q</I> with the self-field <I>I</I><SUB>c0</SUB>. The low value of <I>Q</I> in this case is due to the field dependent <I>I</I><SUB>c</SUB> and the saturation effect of the current profiles, which results in significant reduction of the induced magnetic moment, <I>M</I>. </P>